Improved paper for postage-stamps



UNITE STATES PATENT OFFICE,

HENRY LOEWENBERG, OF NEW YORK, N. Y., ASSIGNOR TO HIMSELF AND EMILE GRANIER, OF SAME PLACE.

IMPROVED PAPER FOR POSTAGE-STAMPS.

Specification forming part of Letters Patent No. 53,08], dated March 6, 1866.

To all whom it may concern:

Be it known that 1, HENRY LOEWENBERG, of the city, county, and State of New York, have invented a new and useful Mode of Preparing Paper for the Purpose of Preventing Alterations of any Figures, Letters, Writing, Characters, or Designs which may be traced. or written or printed upon said prepared paper, or which may be both printed and written thereon.

The nature of my invention consists in the preparation of the paper, either in the process of manufacture, or subsequently, with prussiate of potash, and with oxalic acid or other mordant, separately or mixed, or such other alkaline salts or acids as will combine with any writing or printing ink subsequently used upon the paper, so that when any such chemical agents as would remove writing or printing ink from ordinary paper, or any other chemical agents for such purpose, are applied to this prepared paper they will instantly discolor the paper, and instead of removing will affix such writing or printing ink to the paper more firmly. This discoloration of the paper will be permanent, and may be made of so deep a tint as to detect at once the attempted fraud, and thereby prevent it, and the printing or writing itself may be disfigured, according to the purpose intended.

I am aware that alkaline salts or their equivalent have been heretofore used for the purpose of affixing the ink to the paper, but, without risk of detection,'such ink may be, notwithstanding, removed by certain acids from that paper, so that it is ineffectual for the purpose proposed; but by my invention the print or canceling-mark cannot beremoved without discoloring the paper, and thus exposing the attempted fraud. I

This invention will be useful for bank-bills, checks, drafts, notes, stamps for revenue, postal, and other purposes, to prevent the alteration of such bills and checks and the removal of canceling-marks from stamps.

What I claim as new is-- The use of prussiate of potash and oxalic acid, or such other alkaline salts or acids, in or on the paper to be used for writing or printing or both, so that when any attempt is made by the use of any chemical agents to remove such writing or printing, or both, the paper will perceptibly change its color, but the writing will be more aftixed to the paper.

nnvnr LOEWENBERG. [L. s]

Witnesses:

P. G. GALPIN, Tnos. D. JAMES. 

